I can do three to five good posts in an hour twice a day but and this is a big but you need to find posts to reply to with a good viable reply. Sometimes you can’t find a topic on the front page of a section say meta economics and bitcoin technical help.
You're right three to five good posts aren't difficult especially for someone like you who makes a lot of posts on daily basis. It sometimes depends on the replies that we make because in some topics we get involved so deeply that making out 3-5 posts in a single thread isn't hard for us while other times we may make a single reply in a thread and no more than that.
I mostly post in Meta, Bitcoin discussion, and Gambling boards but sometimes I try to post in other boards as well. I believe that it depends on our moods and our understanding about a topic. If we are well aware of a topic then the replies come naturally and we don't really need to put much effort while sometimes we'll have to give time to research in order to make a proper reply.
I believe that even top posters won't be able to make 10 constructive posts in an hour because we as humans need to have some rest after making some posts. I usually make 1-2 posts or sometimes more at a time and then I take rest and do other activities of my life before making any further posts.
Ten good posts in an hour would be very hard to do even for me.
Now I could write 25 good posts onto notes in a day and drop them all in an hour and it would really look like burst posting since no one would see that I spent 2 hours writing the posts.
I post in James Joyce style often so it does allow for water posting.
Human does not have such capability. 
